Low dye retention sub for photographic film



g- 1939- G. F. NAD EAU' 2,169,004 I LOW DYE RETENTION SUB FOR PHQTOGRAPHIC FILM Filed Odt. 21, 1958 Fig.1.

V EMULSION G'ELAWN CELLl/LOSEN/TRATEAND .SVNTHETIC'RESIN NOTCON7i4/N/NG' A CARBOXYL GROUP w 10 fi'fCELLULOSE DERIVATIVE SUPPORT 14EMULSION 13 K 6'ELAT/N l v, CELLULOSE N/TRATE AND 1/ POLYVINYL ACETATEJJ fi h)" CELLULOSE ORGAN/C DERIVATIVE SUPPORT F 19. 5. 18 I 5w:SENSITIVE EMULSION EEN SENSITIVE EMULSION o SENSITIVE EMULSION v GELAT/NI CELLULOSE NIT/Z475, AND SYNTHETIC RES/N? 11 NOT co/vm/rmya A CARBOXYLGROUP wn nap cm umf'oRcAN/c DER/I44 TIVE suPPom Patented Aug. 8, 3&39

' UNITED STATES LOW DYE aE'rEN'rioN SUB FOR Pno'roGaArnIc FILM Gale F.Nadeau, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester,N. Y., a corporation of New Jersey Application October 21, 1938, SerialNo. 236,265

12 Claims.

This invention relates to a method for subbing photographic film andparticularly to a sub for film designed to receive a coloredphotographic image.

The problem of producing a photographic safety film base possessingsatisfactory stripping and brittleness qualities has been an extremelydifiicult one. In order to cause photographic emulsion layers to adhereto cellulose organic acid b ester supports, it is necessary to useintervening layersof such character that the several layers do not stripfrom the support when the film is used or when it is passed throughprocessing baths and also of such character that the layers i do notadhere with such firmness that the film becomes brittle. One successfulway of making a photographic film having satisfactory stripping andbrittleness properties is to use a synthetic resinous material as a subor undercoat, as described in my prior application Serial No. 1547.

In the case of photographic film having an emulsion layer or severalemulsion layers designed to receive, colored photographic images, thesubbing or undercoat layers must possess additional 5 qualities. The dyeor other coloring material used in the emulsion layers is likely tostain the sub or undercoat if it is not properly constructed and the subor undercoat may also cause fading of the dye in the emulsion layer ofthe film next to the sub, when the film is incubated or stored afterprocessing.

It is, therefore, an object of the present invention to provide a sub orundercoat for a photographic safety film having an emulsion layer orlayers designed to receive colored images, which does not retain a dye"stain caused by the colored image. A further object is to provide asubbing layer which does not cause the dye in an overcoat emulsion layerto fade or bleach during storage of the finished film. A still furtherobject is to provide a safety film having satisfactory stripping andbrittleness characteristics. Other objects will appear from thefollowingdescription of my invention.

,, These objects are accomplished according to my invention by providinga subbing layer of a mixture of cellulose nitrate and a synthetic resinnot containing a carboxyl group. The layer is coated directly on acellulose organic acid ester film base and other suitable layers arecoated over it.

3 In. the accompanying drawing Figs. 1, 2 and 3 are sectional views of aphotographic film having subbing layers thereon according to my inven-In subbing film according to my invention a cellulose derivative supportof any composition is coated with the subbing or undercoat layer ofcellulose nitrate and the synthetic resin. The support may consist ofcellulose nitrate or other 5 inorganic acid ester of cellulose, but acellulose organic acid ester will ordinarily be used with a sub of thistype. The cellulose organic derivative support may be a simple ester,such as cellulose acetate or a mixed ester, such as cellulose acetate l0propionate or cellulose acetate butyrate. I

The subbing layer first applied consists of a uniform mixture of a highalcohol soluble, low viscosity cellulose nitrate and a synthetic resinnot containing a carboxyl group. I have found that the resins containingcarboxyl groups are not suitable for subbing according to'my inventionsince they tend to stain and, therefore, render'the film unfit for useas coior film. Among the synthetic resins which may be used are thefollowing. The polyvinyl esters, such as polymer ized vinyl acetatewhich is known, for example, under the trade name Gelva, the preparationof which is described in the U. S. Patent Nos. 1,241,738; 1,586,803 and1,710,825. A further type of resin which may be used is the polyvinylacetal type. These resins are condensation products of partially orcompletely hydrolyzed polyvinyl acetate and an aldehyde, such asformaldehyde, acetaldehyde, or butyraldehyde and are known as polyvinylacetals. They are sold under various trade names such as Formvari andAlvar, the preparationof which is described in British Patent No.351,082 and in U. S. Patents Nos. 1,955,- 068 and 1,990,399. A stillfurther type of resin is the group known as the Santolites which arecondensation products of formaldehyde with aromatic sulfonamides. I mayalso use the polyacrylic esters, such as the methyl or butyl esters ofpolyacrylic acid. 49

After drying, the layer of cellulose nitrate and synthetic resin may becoated with a cellulose nitrate layer other layer or a gelatin layer maybe coated directly on it. The gelatin layer is fol lowed by a coating ofone or more emulsion layers 5 designed to record a colored photographicimage.

My invention will now be described by particular reference to theaccompanying drawing. As shown therein a support ID of any suitablematerial such as cellulose nitrate or cellulose acetate o is coated witha layer 12 of cellulose nitrate and a synthetic resin not containing acarboxyl group.

On this layer there is coated a gelatin layer l3 and a gelatino-silverhalide emulsion layer It.

According to the modification shown in Fig. 5b

2 a support ll of an organic acid ester derivative of cellulose, such ascellulose acetate or cellulose acetate propionate, is coated with alayer I5 of cellulose nitrate and polyvinyl acetate. 3 This layer isthen coated with the gelatin subbing layer i 3 and emulsion layer M.

Fig. 3 shows a film designed for multi-color photography in which thesupport II is coated with the subbing layer l2 of cellulose nitrate anda synthetic resin not containing a carboxyl group, and this is followedby the, gelatin layer l3. On the gelatin layer I3 are coated insuccession a red sensitive silver halide emulsion layer IS,

other layers, such as intermediate filter layers,

which may be necessary to prevent the action of light of any spectralcolor on any of the layers of 4 the film.

As stated above, the subbing layer applied directly to the film baseconsists of a mixture of cellulose nitrate and a synthetic resin notcontaining a carboxyl group. The cellulose nitrate is of the highalcohol soluble, low viscosity type which may have the followingcomposition:

. Range Alcohol solubility per cent 30-100 Viscosity (dropping ball) sec2-5 Nitrogen 11.0-12.0

The resin and nitrate undercoat is coated on the film base from asuitable solvent or solvent mixture, such as acetone, acetone andmethanol;

acetone and methyl alcohol, ethylene dichloride with methyl alcohol orethyl alcohol, and various combinations o1 these solvents together withmethyl Cellosolve. A suitable solvent mixture consists of 40 partsacetone and parts of methyl alcohol. I

The concentration of the subbing solution adjusted to the speed ofcoating and may vary 'fromabou't 2% to about 6% or more of nitrate andresin in the solution. The sub is coated at a linear speed of from 3 to10 feet per minute and a layer which may vary in thickness from 0.00006inch to 0.00015 inch is thereby obtained.

The gelatin --sub coated over thenitrate-resin layer may have thefollowing composition:

- Per cent Gelatin -'1.2 Acetic acid 2 Water 12 Methyl alcohol "-84.8

The emulsion layer coated over the gelatin sub may consist of anordinarygelatinosilver halide emulsion or it may be sensitized to recordvarious regions of the spectrum. In the case of multilayer iilm, thesuccessive emulsion layers applied to the gelatin sub may bedifferentially sensitized and may or may not contain dyes or colorforming compounds designed to produce a colored photographic image orimages in the layers. The

film may also have other layers, such as filters,

' overcoating layers, or 'anti'-halation1 layers applied thereto.

My invention will be further understood by reference to the followingspecific examples which are understood to be illustrative only.

Example I A photographic film base of cellulose acetate containing about40.5% acetyl was coated with the following subbing solution:

Grams Polyvinyl acetate 1.2 Cellulose nitrate 1.2 Acetone 38.8Methanol--- 58.8

This solution was coated at a linear speed of 6 feet per minute and wasdried after coating. A gelatin subbing layer having the followingcomposition was then applied:

Per cent Gelatin 1.2 Acetic acid 2 Water 12 Methyl alcohol 84.8

Over the gelatin layer there was then coated a gelatino silver halideemulsion layer. The film produced in this way was found to havesatisfactory stripping and brittleness properties and when a coloredimage was formed in the sensitive emulsion layer,- the dye was notretained by the subbing layer.

. Example I! A photographic film base of cellulose acetate 'propionatecontaining 16% propionyl and 29% acetyl was coated with, a subbingsolution having the following composition:

Grams Polymethyl acrylate 2 Cellulose nitrate 4.6 Acetone 93.4

After drying, there was coated on this layer a solution of gelatinhaving the same composition as that in Example I and successive layersof red green sensitive layer and the red sensitive layer.

'Ihave referred to satisfactory stripping and brittleness properties"throughout the specification. It is to be understood that this term,although not susceptible of precise definition, nevertheless has adefinitely accepted meaning in the photographic art, and that film canbe tested to determine whether it is commercially satisfactory withrespect to stripping and brittleness. Tests to which the film may besubjected for this purpose are outlined in my prior U. S. Patent No.2,096,616, granted October 19, 1937.

I have also referred above to the "dropping ball method" for determiningthe viscosity of cellulose nitrate. The "dropping ball method" foriletermining viscosity oi. cellulose nitrate is as-folows:

110 grams 01' dry nitro cellulose is dissolved in cc. oi a mixturecomprising 50% by volume of methyl alcohol and 50% by volume of acetoneat -25 C. Viscosity is measured by the time in seconds it takes for; asteel ball having a dive'ntion has a number 01' important advantages.

tain-any dye which is used in the emulsion layers to form colorphotographic images and does not cause fading of the dye contained inthese layers, my subbing method also has other advantages. For example,the mixture of 'i'esin and nitrate can be conveniently handled incoating machines as it is not tacky and does not adhere to the machineparts. The-resulting film is not brittle althoughthe emulsionadhereswell to the base. The wearing qualities of motion picture filmmade in this way are very good and film was found to be.

in good condition after having been passed through a projector a numberof times.

I have referred in the present description of my invention, to subbingsafety filmsupport, that is, cellulose organic acid ester film support,as constituting the preferred embodiment of my invention. However,although the problem of sub-' bing cellulose inorganic acid estersupports is usually not so difllcult as in the case of cellulose or--ganic acid esters,- the matter of staining the sup-' port in colorprocesses must be considered. I

have found that the use of subs according to my invention, prevents dyestaining of cellulose nitrate supports as well as supports of celluloseorganic acid esters. I

I-have also referred to the use of my subbing method in film designed toreceive colored images. Film support may also be subbed according to myinvention where the film is designed to record black-and-white silverimages.

It is to be understood that the above examples, ranges, and methods ofprocedure are illustrative only and that my invention is to be taken aslimited only by the scope of the appended claims.

Having thus described 'my invention, what I I declare is new and desireto secure by Letters Patout of the United States is:'

1. A photographic film for use in color photography having low dyeretention subbing layers, comprising acellulose ester support, anemulsion layer adaptedto receive a colored image, and between saidsupport and said. emulsion layer, a subbing layer of a mixture ofcellulose nitrate and a synthetic resin free of carboxyl groups.

2. A photographic film for use in color photography having low dyeretention subbing layers,

comprising a cellulose organic ester support, a subbing layer of amixture of cellulose nitrate and a synthetic resin free of carboxylgroups directly attached to said support, a gelatin layer attached tosaid subbing layer, and an emulsion layer adapted to receive a coloredimage'attached to said gelatin layer.

3. A photographic film for use in color photography having low dyeretention subbing layers, comprising af cellulose organic acid estersupport, and in order thereon, a subbing "layer of a. mixture ofcellulose nitrate and a synthetic resin tree of carboxyl groups, theresin in the sub being present in not greater amount than the cellulosenitrate, a gelatin layer, and an emulsion layer adapted to receive acolored image.

4. A photographic film for use in color photography having-low dyeretention subbing layers, comprising a cellulose organic acid estersupport, and in order thereon, a subbing layer of a mixture of cellulosenitrate and asynthetic resin free or 'carbonl groups, the resin and thenitrate being present in substantially equal amounts, at gellatin 5. Aphotographic film for use in color photography having low dyeretentionsubbing layers, comprising a cellulose organic acid ester support, andin order thereon, a subbing layer of a mixture of cellulose nitrate anda synthetic resin free of carboxyl groups, a gelatin layer, and a.plurality of diilerentially sensitized emulsion-layers.

. 6. A photographic film for use in color photography having low dyeretention subbing layers, comprising a cellulose organic acid estersupport, and in order'thereon, a subbing layer of, a mixture ofcellulose nitrate and a synthetic resin free of carboxylgroups, theresin and the nitrate being present in equal amounts, a gelatin layer;and a plurality of emulsion layers sensitized to record differentregions of the spectrum.

7., A photographic film for use in color photography having low dy'eretention subbing layers,

comprising a cellulose organic acid ester support, and in order thereon,asubbing layer of a mixture ofcellulose nitrate and a polyvinyl acetateresin, a gelatinlayer, and a plurality of emulsion layers sensitized torecord diiferent regions of the spectrum. 1 8. A photographic film foruse in color photography having low dye retention subbinglayers,comprising a cellulose organic acid ester support,

and in order thereon, a subbing layer of a mixture of cellulose nitrateand a polyvinyl acetate resin, the resin. being present in less amountthan the cellulose nitrate, a gelatin layen and a plurality of emulsionlayers sensitized to record different regions of the spectrum.

9. A photographic film" having satisfactory stripping andbrittleness-properties, comprising a cellulose organic acid ester filmsupport and a sensitive emulsion layer, and between said support andsaid emulsion layer, successive layers of a mixtureof cellulose nitrateand asynthetic resin free of carboxyl groups, and a gelatin layer.

10. A photographic film having satisfactory stripping and brittlenessproperties comprising a cellulose organic acid ester support, a subbinglayer of a mixture 01' cellulose nitrate and a synthetic resin free ofcarboxyl groups coated I directly on said support, said subbing layerhav-;

ing a thickness of from 0.00006 inch to 0.00015 subbing layer, and asensitive emulsion layerattography having low dye retention subbinglayers,

comprising a cellulose inorganic acid ester support, a' subbing layer ofa mixture of cellulose nitrate and a synthetic resin, free of carboxylgroups directly attached to said support, a gelatin layer attached tosaid subbing layer, and an emulsiori layer adapted to receive a coloredimage at: tached to said gelatin layer.

12. A photographic film for use in color photography liaving low dyeretention subbing layers, comprising a cellulose nitrate support, and inorder thereon, a subbing layer' of a mixture of cellulose nitrate and asynthetic resin free-or carboxyl groups, a. gelatin layer, and aplurality of emulsion layerssensitized to record different 1 inch, agelatin layer attached directly, to said

